683548 divided by 21 
The aim is to understand the frequency of 21 in 683548.

Moving on to step 1:
21 can be fit into 6 0 times, resulting in a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Take the next digit (8) from the dividend and append it to 6, then repeat: 68 / 21

On to step 2:
The number 21 fits into 68 3 times, leaving a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Deduct 63 from 68 and we're left with 5.
Include the next digit (3) from the dividend after 5, then repeat: 53 / 21

Moving on to step 3:
The number 21 fits into 53 2 times, leaving a remainder of 11.
Put 2 as the next digit of the answer. 
Result so far: 32.0
Subtract 42 from 53 to get 11.
Grab the next digit (5) from the dividend, add it to 11, then carry on: 115 / 21

Moving on to step 4:
When dividing 115 by 21, we get 5 with a remainder of 10.
Record the quotient 5 as the next digit in the result. 
Result so far: 325.0
Deduct 105 from 115 and we're left with 10.
Append the next digit (4) from the dividend to 10 and continue with: 104 / 21

Advancing to step 5:
When dividing 104 by 21, we get 4 with a remainder of 20.
Put 4 as the next digit of the answer. 
Result so far: 3254.0
The remainder is 20 after subtracting 84 from 104.
Fetch the next digit (8) from the dividend, attach it to 20 and continue: 208 / 21

On to step 6:
21 goes into 208 9 times with a remainder of 19.
Use 9 as the next digit of our solution. 
Result so far: 32549.0
Subtracting 189 from 208 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 7:
21 goes into 190 9 times with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 32549.9
The remainder is 1 after subtracting 189 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 8:
If we divide 10 by 21, we get 0 and a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 32549.9
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 9:
The number 21 fits into 100 4 times, leaving a remainder of 16.
The next digit of our result is 4. 
Result so far: 32549.904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 10:
21 can be fit into 160 7 times, resulting in a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 32549.9047
Subtracting 147 from 160 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Moving on to step 11:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 32549.90476
Deduct 126 from 130 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 12:
40 divided by 21 is 1 with a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 32549.904761
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 13:
190 divided by 21 is 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 32549.9047619
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 14:
10 divided by 21 is 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 32549.9047619
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final outcome is 32549.9047619, with a leftover of 1e-08.